> They cost like 3x what a newbuild does, this "but building codes" stuff doesnt stand up to scruitiny.

I don't think that's a fair comparison. There is a fixed supply by definition of those old buildings, so their price will be pushed up by demand with little relation to their cost to build since they can't be built anymore.

A better comparison would be to look at the cost of new houses in developing places like SE Asia where there are little to no building codes.